USE OF LACCASE IN BAKING

Abstract: A dough- or bread-improving composition comprising laccase as well as the use of the composition in the preparation of dough and backed products.

Description: USE OF LACCASE IN BAKING FIELD OF THE INVENTION The present invention relates to a bread-improving or dough- improving composition comprising an enzyme as well as to a method of preparing a dough and/or a baked product by use of the composition. BACKGROUND OF THE INVENTION In the bread-making process it is known to add bread-improving and/or dough-improving additives to the bread dough, the action of which, inter alia, results in improved texture, volume, flavour and freshness of the bread as well as improved machinability of the dough. In recent years a number of enzymes have been used as dough and/or bread improving agents, in particular enzymes which act on components present in large amounts in the dough. Examples of such enzymes are found within the groups of amylases, proteases and cellulases, including pentosanases. Laccase (EC 1.10.3.2) is an enzyme catalyzing the conversion of benzenediols into benzosemiquinones according to the following formula: 4 benzenediol + 0 2 = 4 benzose iquinone + 2H 2 0. The enzyme has been used in the paper and pulp industry as well as for diagnosis, but the use of the enzyme in baking has never been suggested. It is the object of the present invention to improve the properties of dough and/or baked products by the use of a laccase enzyme. BRIEF DISCLOSURE OF THE INVENTION Accordingly, in a first aspect the present invention relates to a bread-improving and/or a dough-improving composition compri¬ sing a laccase enzyme. In the present context the terms "bread-improving composition" and "dough-improving composition" are intended to indicate compositions which, in addition to the enzyme component, may comprise other substances conventionally used in baking to improve the properties of dough and/or baked products. Examples of such components are given below. Without being limited to any theory it is presently contem¬ plated that when a laccase enzyme is added to dough used for producing baked products, it may exert an oxidizing effect on dough constituents and thereby serve to, e.g., improve the strength of gluten structures in dough and/or baked products. Further improved properties may also be shown to be obtained. In the present context the term "improved properties" is intended to indicate any property which may be improved by the action of a laccase enzyme. In particular, the use of laccase results in an increased volume and an improved crumb structure and softness of the baked product, as well as an increased strength, stability and reduced stickiness and thereby improved machinability of the dough. The effect on the dough has been found to be particularly good when a poor quality flour has been used. The improved machinability is of particular import¬ ance in connection with dough which is to be processed indus¬ trially. The improved properties are evaluated by comparison with dough and/or baked products prepared without addition of laccase in accordance with the present invention. In a second aspect, the present invention relates to a method of preparing a dough and/or a baked product prepared from the dough comprising adding a laccase enzyme, optionally present in a bread-improving or dough-improving composition, to the dough and/or to any ingredient of the dough and/or to any mixture of the dough ingredients. In further aspects, the present invention relates to a dough and a baked product, respectively, produced by the present method as well as to a pre- ix comprising a laccase enzyme. In the present context, the term "pre-mix" is intended to be understood in it's conventional meaning, i.e. as a mix of baking agents, normally including flour, which may be used not only in industrial bread-baking plants/facilities, but also in retail bakeries. In a final aspect, the present invention relates to the use of a laccase enzyme for the preparation of dough and/or baked products. DETAILED DISCLOSURE OF THE INVENTION While the laccase enzyme of the dough- and/or bread-improving composition of the invention may be of any origin, including plant origin, it is presently preferred that the laccase enzyme is of microbial origin. Thus, a microbial enzyme is normally easier to produce on a large scale than a non-microbial enzyme of, e.g., plant origin. Furthermore, the microbial enzyme may normally be obtained in a higher purity than enzymes of other origins, resulting in a lower amount of undesirable enzymatic side-activities. The microbial laccase enzyme may be derived from bacteria or fungi (including filamentous fungi and yeasts) and suitable examples include a laccase derivable from a strain of Aspergil- lus , Neurospora , e.g. N. crassa Podospora , Botrytis , Collybia , Fomes, Lentinuε , Lentxnus , Pleurqtus, Trameteε, Rhizoctonia , e.g. -R. solani , Coprinus, e.g. C. plicatiliε , Psatyrella, Myceliophtera , e.g. M. thermophila , Schytalidium, Polypo ns . e.g. P . pinsitus , Phlebia , e.g. P . radita (WO 92/01046) , or Coriolus, e.g. C .hirsutus (JP 2-238885) . The laccase may be obtained from the microorganism in question by use of any suitable technique. For instance, a laccase preparation may be obtained by fermentation of a microorganism and subsequent isolation of a laccase containing preparation from the resulting fermented broth or microorganism by methods known in the art, but more preferably by use of recombinant DNA techniques as known in the art. Such method normally comprises cultivation of a host cell transformed with a recombinant DNA vector capable of expressing and carrying a DNA sequence encoding the laccase in question, in a culture medium under conditions permitting the expression of the enzyme and recov¬ ering the enzyme from the culture. The DNA sequence may be of genomic, CDNA or synthetic origin or any mixture of these, and may be isolated or synthesized in accordance with methods known in the art. The laccase enzyme to be included in the bread-improving and/or dough-improving composition of the invention may be in any form suited for the use in question, e.g. in the form of a dry powder or granulate, in particular a non-dusting granulate, a liquid, in particular a stabilized liquid, or a protected enzyme. Granulates may be produced, e.g. as disclosed in US 4,106,991 and US 4,661,452 (both to Novo Industri A/S), and may optionally be coated by methods known in the art. Liquid enzyme preparations may, for instance, be stabilized by adding nutritionally acceptable stabilizers such as a sugar, a sugar alcohol or another polyol, lactic acid or another organic acid according to established methods. Protected enzymes may be prepared according to the method disclosed in EP 238,216. Normally, for inclusion in pre-mixes or flour it is advan¬ tageous that the laccase enzyme preparation is in the form of a dry product, e.g. a non-dusting granulate, whereas for inclu- sion together with a liquid it is advantageously in a liquid form. The bread- and/or dough-improving composition of the invention may further comprise another enzyme. Examples of other enzymes are a cellulase, a he icellulase, a pentosanase (useful for the partial hydrolysis of pentosans which increases the extensibility of the dough) , a glucose oxidase (useful for strengthening the dough) , a lipase (useful for the modification of lipids present in the dough or dough constituents so as to soften the dough) , a peroxidase (useful for improving the dough consistency) , a protease (useful for gluten weakening, in particular when using hard wheat flour) , a peptidase and/or an amylase, e.g. α-amylase (useful for providing sugars fermentable by yeast) . The other enzyme components are preferably of microbial origin and may be obtained by conventional techniques used in the art as mentioned above. In a particular embodiment, the other enzyme component(s) may be produced from the same source as the laccase in question and recovered together with the laccase. In addition or in an alternative to other enzyme components, the dough-improving and/or bread-improving composition may com¬ prise a conventionally used baking agent, e.g. one or more of the following constituents: A milk powder (providing crust colour) , gluten (to improve the gas retention power of weak flours) , an emulsifier (to improve dough extensibility and to some extent the consistency of the resulting bread) , granulated fat (for dough softening and consistency of bread) , an oxidant (added to strengthen the gluten structure; e.g. ascorbic acid, potassium bromate, potassium iodate or ammonium persulfate) , an amino acid (e.g. cysteine) , a sugar, and salt (e.g. sodium chloride, calcium acetate, sodium sulfate or calcium sulfate serving to make the dough firmer) , flour or starch. Examples of suitable emulsifiers are mono- or diglycerides, diacetyl tartaric acid esters of mono- or diglycerides, sugar esters of fatty acids, polyglycerol esters of fatty acids, lactic acid esters of monoglycerides, acetic acid esters of monoglycerides, polyoxyethylene stearates, phospholipids and lecithin. The bread-improving and/or dough improving composition of the invention is typically included in the dough in an amount corresponding to 0.1-5%, such as 0.1-3% of the amount of flour to be added and typically comprises 0.5-30,000 Laccase Units per gramme. In accordance with the method of the invention, in which laccase is used for the preparation of dough and/or baked products, the enzyme may be added as such to the mixture from which the dough is made. Alternatively, the laccase enzyme may be added as a constituent of a dough-improving and/or a bread- improving composition as described above. The dosage of the laccase enzyme to be used in the method of the present invention should be adapted to the nature and composition of the dough in question. Normally, the enzyme preparation is added in an amount corresponding to 5-100,000 Laccase Units. The Laccase Units (LACU) may be determined by the assay described below in the Materials and Methods section. It is preferred that the laccase enzyme is added in an amount corresponding to 50-20,000 LACU, such as 50-30,000 LACU, and in particular 100-1500 LACU per kg of flour. When one or more additional enzyme activities are to be added in accordance with the method of the invention, these activ¬ ities may be added separately or together with the laccase preparation, optionally as constituent(s) of the bread-impro¬ ving and/or dough-improving composition of the invention. The other enzyme activities may be any of the above described enzymes and may be dosed in accordance with established baking practice. As mentioned above the laccase enzyme is added to any mixture of dough ingredients, to the dough, or to any of the ingredi¬ ents to be included in the dough, in other words the laccase enzyme may be added in any step of the dough preparation and may be added in one, two or more steps, where appropriate. However, the enzyme should not be added together with any strong chemical or under conditions where the enzyme is inactivated. The handling of the dough and/or baking is performed in any suitable manner for the dough and/or baked product in question, typically including the steps of kneading the dough, subjecting the dough to one or more proofing treatments, and baking the product under suitable conditions, i.e. at a suitable tempera¬ ture and for a sufficient period of time. For instance, the dough may be prepared by using a normal straight dough process, a sour dough process, an overnight dough method, a low-tempera- ture and long-time fermentation method, a frozen dough method, the Chorleywood Bread process, and the Sponge and Dough process. The dough and/or baked product prepared by the method of the invention are normally based on wheat meal or flour, optionally in combination with other types of meal or flour such as corn flour, rye meal, rye flour, oat flour or meal, soy flour, sorghum meal or flour, or potato meal or flour. However, it is contemplated that the method of the present invention will function equally well in the preparation of dough and baked products primarily based on other meals or flours, such as corn meal or flour, rye meal or flour, or any other types such as the types of meal or flour mentioned above. In the present context the term "baked product" is intended to include any product prepared from dough, either of a soft or a crisp character. Examples of baked products, whether of a white, light or dark type, which may advantageously be produced by the present invention are bread (in particular white, whole¬ meal or rye bread) , typically in the form of loaves or rolls, French baguette-type bread, pita bread, tacos, cakes, pan¬ cakes, biscuits, crisp bread and the like. The dough of the invention may be of any of the types discussed above, and may be fresh or frozen. From the above disclosure it will be apparent that the dough of the invention is normally a leavened dough or a dough to be subjected to leavening. The dough may be leavened in various ways such as by adding sodium bicarbonate or the like or by adding a leaven (fermenting dough) , but it is preferred to leaven the dough by adding a suitable yeast culture such as a culture of Saccharomyces cerevisiae (baker's yeast) . Any of the commercially available S . cereviciae strains may be employed. As mentioned above, the present invention further relates to a pre-mix, e.g. in the form of a flour composition, for dough and or baked products made from dough, which pre-mix comprises a laccase enzyme. The pre-mix may be prepared by mixing a laccase preparation or a bread-improving and/or dough-improving composition of the invention comprising laccase with a suitable carrier such as flour, starch, a sugar or a salt. The pre-mix may contain other dough-improving and/or bread-improving additives, e.g. any of the additives, including enzymes, mentioned above. In a further aspect the invention relates to the use of a laccase enzyme for improving properties of a dough and/or a baked product made therefrom. The type of laccase as well as the manner in which it may be used is described in detail above. In a final aspect the invention relates to the use of laccase for the preparation of pasta dough, preferably prepared from durum flour or a flour of comparable quality. The dough may be prepared by use of conventional techniques and the laccase used in a similar dosage as that described above. The laccase is preferably of microbial origin, e.g. as disclosed herein. It is contemplated that when used in the preparation of pasta the laccase results in a strengthening of the gluten structure and thus a reduction in the dough stickiness and an increased dough strength. MATERIALS AND METHODS Enzymes Laccase: A Rhizoctonia solani laccase produced by the Rhizocto- nxa solani strain RS22 deposited with the International Mycological Institute, Genetic Resource Reference Collection, located at Bakeham Lane, Egham Surrey TW20 9TY on September 3, 1993 under the terms of the Budapest Treaty and given the accession number IMI CC 358730. The Rhizoctonia solani laccase is further described in co-pending application (US serial number 08/172,331) , the contents of which is hereby incorpor¬ ated by reference. Xylanase: A xylanase produced by the Humicola insolens strain DSM 1800 available from the Deutsche Sammlung von Mikroor- ganismen und Zellkulturen GmbH and further described in EP 507 723. Pentosanase: Pentopan® available from Novo Nordisk A/S. Fungamyl: A commercial fungal -amylase preparation available from Novo Nordisk A/S. Determination of laccase activity Laccase activity is determined by incubating a laccase contain¬ ing sample with syringaldazin (19 μM, Sigma No. S 7896) under aerobic conditions (30°C, 1 min., pH 5.5), whereby the syrin- 5 galdazin is oxidized to tetramethoxy azo bis-methylene quinone. The absorbance is measured at 530 nm after 15 and 75 seconds and the difference between the measured values is proportional with the laccase units per ml or grammes of sample. 1 Laccase Unit (LACU) is the amount of enzyme which, under the 10 prescribed reaction conditions, converts 1 μM syringaldazin per minute. PAU - Fungal alpha-Amylase Units 1 FA-unit (FAU) is the amount of enzyme which at 37°C and pH 4.7 breaks down 5260 mg of solid starch per hour. 15 FXU - xylanase activity The endo-xylanase activity is determined by an assay, in which the xylanase sample is incubated with a remazol-xylan substrate (4-O-methyl-D-glucurono-D-xylan dyed with Remazol Brilliant Blue R, Fluka) , pH 6.0. The incubation is performed at 50°C for 2030 min. The background of non-degraded dyed substrate is precipitated by ethanol. The remaining blue colour in the supernatant is determined spectrophoto etrically at 585 nm and is proportional to the endoxylanase activity. The endoxylanase activity of the sample is determined rela- 25 tively to an enzyme standard. Preparation of bread Procedure 1. Dough mixing (Spiral mixer) 3 min. at 700 RPM 8 min. at 1400 RPM the mixing time was determined and adjusted by a skilled baker so as to obtain an optimum dough consistence under the testing conditions used. 2. 1st proof: 30°C - 80% RH, 20 min. 3. Scaling and shaping; 4. Final proof: 32°C - 80% RH, 40 min.; 5. Baking: 225°C, 20 min. for rolls and 30 min for loaf. Evaluation of dough and baked products Dough and baked products described in the examples were evalu- ated as follows: Loaf specific volume: the mean value of 4 loaves volume are measured using the traditional rape seed method. The specific volume is calculated as volume ml per g bread. The specific volume of the control (without enzyme) is defined as 100. The relative specific volume index is calculated as: specific vol. of 4 loaves Specific vol. index —*100 spec. vol. of 4 control loaves The dough stickiness and crumb structure are evaluated visually according to the following scale: Dough stickiness: almost liquid 1 too sticky 2 sticky 3 normal 4 dry 5 Crumb structure : very poor 1 poor 2 non-uniform 3 uniform/good 4 very good 5 Shock test: After the second proof a pan containing the dough is dropped from a height of 20 cm. The dough is baked and the volume of the resulting bread is determined. EXAMPLES EXAMPLE 1 Wheat flour pan bread Recipe Wheat flour 100 % Yeast 4 % Salt 1.5 % Sugar 1.5 % Water 59 % Flour type: Pastetli-Intermid without ascorbic acid (Intermill, Schweiz) . Table 1 Laccase LACU/kg 0 600 1000 flour Specific volume 100 100 107 index After shock Specific volume 100 109 106 index Crust crispy normal improved improved Laccase has a significant effect on improving the baking quality of flour without oxidant. The dough stability is improved by the addition of laccase, because the bread with laccase regain more volume than the control after the dough have been shocked. EXAMPLE 2 Whole meal bread Recipe Whole meal flour (Intermill-Graham) 100 % Yeast 4 % Salt 2 % Malt 1 % Gluten 3 % Water 75 % Table 2 Laccase LACU/kg flour 0 500 1000 1000 1000 0 Pentopan g/kg flour 0 0.15 Fungamyl FAU/kg flour 15 15 Specific volume index 100 101 101 105 108 110 after shock, Specific 100 105 108 106 109 105 volume index For the whole meal bread, addition of laccase reduces dough stickiness during dough handling. Furthermore, the dough becomes more stable (as shown by the fact that bread treated with laccase can regain more volume compared to the control after shock test) . EXAMPLE 3 Bread prepared with wheat flour containing ascorbic acid The wheat flour used was Manitaba flour, a Danish baking flour with ascorbic acid (avaible from Valse øllerne A/S, Denmark) . Table 3 Lac¬ LACU/kg 0 100 1000 1000 1000 case fl. 0 Pento- g/kg fl. 0 0.15 0.15 pan Xylan¬ FXU/kg 0 50 50 ase fl. Funga- FAU/kg 0 30 30 myl fl. Dough 4 4.5 4 3.5 4 3.5 4.5 3 sticki¬ ness Sp.vol- 100 104 116 116 117 117 112 111 .ind Crumb 3 4 4 4 4 4 4 3.5 struc¬ ture Dough 4 4 4 3.5 4.5 3.5 4 3.5 firm¬ ness Addition of laccase reduces the dough stickiness. Enzymes such as pentosanase/ xylanase and fungal amylase can cause dough stickiness and dough softness. When combining laccase with one of these enzymes the dough became normal. This is desirable for baking processes in which dough stickiness is not acceptable. EXAMPLE 4 Flour Whole wheat flour (Intermill, Schweiz) Prima flour (Havnemøllerne A/S, Denmark) , Reform flour (Havnemøllerne A/S, Denmark) Manitoba flour (Valsemøllerne A/S, Denmark) , Pasteli-flour (Intermill, Schweiz) . Procedure Flour 300 g NaCl 6 g Laccase was used in the amount indicated in the tables. Water was added in an amount sufficient to give a consistency of 500 +/- 20 FU in Brabender Farinograph. Extensograph measurements were conducted 45, 90, and 135 min, respectively, of dough resting. The extensograph used was from Branbender and Duisburg, Germany, and was used as recommended by the manufacturer. The results obtained appear from the following tables. It is evident that the use of laccase increases the dough resistance to extension of dough prepared from different types of flour. The resistance to extension increases with increasing dosages of laccase. TABLE 4 WHOLE WHEAT FLOUR LACCASE PROVING ENERGY RESISTANCE EXTENSIBILITY I MAXIM TIME to EXTENSION (U/kg FLOUR) (min) (cm2) (BU) (mm) (BU) 0 45 56 273 135 273 600 64 333 125 338 1000 64 343 121 348 1500 66 371 117 375 0 90 61 361 114 363 600 74 483 106 487 1000 76 502 107 516 1500 75 534 99 543 0 135 65 393 115 397 600 77 543 101 554 1000 79 572 99 581 1500 73 569 94 573 TABLE 5 REFORM FLOUR Proving Time: 45 min LACCASE ENERGY RESISTANCE EXTENSIBILITY MAXIMUM to EXTENSION (Utkg FLOUR) (cm2) (BU) (mm) (BU) 0 110 494 131 609 600 111 508 128 650 1000 120 562 127 704 1500 112 564 122 669 TABLE 6 "PASTETLP FLOUR LACCASE 1 'ROVING ENERGY RESISTANCE EXTENSIBILITY MAXIMUM TIME to EXTENSION (U kg FLOUR) (min) (cm2) (BU) (mm) (BU) 0 45 86 342 145 403 600 101 385 149 480 1000 101 394 146 492 1500 106 473 133 573 0 90 103 437 144 521 600 114 535 131 631 1000 120 617 125 705 1500 124 758 112 842 0 135 109 499 134 589 600 116 636 118 730 1000 115 707 111 787 1500 121 842 102 906 TABLE 7 MANITOBA Proving Time: 45 min LACCASE ENERGY RESISTANCE EXTENSIBILITY MAXIMUM to EXTENSION (U/kg FLOUR) (cm2 (BU) (mm) (BU) 0 119 421 149 597 600 133 473 148 681 1000 135 519 144 708 1500 135 567 136 748 TAB LE 8 PRiMA FLOUR Proving Time: 45 min LACCASE ENERGY RESISTANCE EXTENSIBIUTY MAXIMUM to EXTENSION (U/kg FLOUR) (cm2) (BU) (mm) (BU) 0 121 496 141 629 600 115 528 127 678 1000 126 565 132 711

Claims: CLAIMS 1. A bread-improving or a dough-improving composition compri¬ sing a laccase enzyme. 2. A bread-improving or dough-improving composition according 5 to claim 1, in which the laccase enzyme is derivable from a microorganism. 3. A bread-improving or dough-improving composition according to claim 2, in which the laccase is derivable from a bacterium or a fungus. 104. A bread-improving or dough-improving composition according to claim 3, in which the laccase is derivable from a strain of Rhizoctonia , Coprinus . Myceliophtera , Polyporus , Coriolus , or Phlebia , e.g. P. radita . 5. The bread-improving or dough-improving composition according 15 to claim 1, which further comprises another enzyme such as a cellulase, a hemicellulase, a pentosanase, a glucose oxidase, a lipase, a peroxidase, a protease, a peptidase and/or an amylase. 6. A bread-improving or dough-improving composition according 20 to claim 1, which further comprises another bread or dough improving agent. 7. A method of preparing a dough and/or a baked product pre¬ pared from the dough comprising adding a laccase enzyme to the dough and/or to any ingredient of the dough and/or to any 25 mixture of the dough ingredients. 8. The method according to claim 7, in which the laccase enzyme is present in a bread-improving or dough-improving composition as defined in any of claims 1-6. 9. The method according to claim 7 or 8, in which the laccase is added in an amount corresponding to 5-100,000 Laccase Units. 10. The method according to claim 7, in which another enzyme or another bread-improving and/or dough improving agent is added to the dough, any ingredient of the dough and/or any mixture of dough ingredients. 11. A dough or baked product prepared from a dough prepared by the method according to any of claims 7-10. 12. A pre-mix for dough comprising a laccase enzyme or a dough- improving composition according to any of claims 1-6. 13. Use of laccase as a dough-improving or bread-improving agent. 14. Use of laccase in the preparation of pasta.

Inventors: SI JOAN QI, SI, JOAN, QI
Applicants: NOVONORDISK AS, SI JOAN QI, NOVO NORDISK A/S, SI, JOAN, QI
Application year: 1994
Main classification: A21D8
IPC codes: A21D8